The subject matter of the present disclosure broadly relates to the art of gas spring devices and, more particularly, to end member assemblies that are constructed to passively alter the spring rate of an associated gas spring assembly from a first spring rate utilized under a first condition of use to a second spring rate upon experiencing an associated event triggering a second condition of use. Gas spring assemblies including such end member assemblies and suspension systems including one or more of such gas spring assemblies as well as methods of manufacture are also included.
The subject matter of the present disclosure may find particular application and use in conjunction with components for wheeled vehicles, and will be shown and described herein with reference thereto. However, it is to be appreciated that the subject matter of the present disclosure is also amenable to use in other applications and environments, and that the specific uses shown and described herein are merely exemplary. For example, the subject matter of the present disclosure could be used in connection with gas spring assemblies of non-wheeled vehicles, support structures, height adjusting systems and actuators associated with industrial machinery, components thereof and/or other such equipment. Accordingly, the subject matter of the present disclosure is not intended to be limited to use associated with suspension systems of wheeled vehicles.
Wheeled motor vehicles of most types and kinds include a sprung mass, such as a body or chassis, for example, and an unsprung mass, such as two or more axles or other wheel-engaging members, for example, with a suspension system disposed therebetween. Typically, a suspension system will include a plurality of spring devices as well as a plurality of damping devices that together permit the sprung and unsprung masses of the vehicle to move in a somewhat controlled manner relative to one another. Generally, the plurality of spring devices function to accommodate forces and loads associated with the operation and use of the vehicle, and the plurality of damping devices are operative to dissipate undesired inputs and movements of the vehicle, particularly during dynamic operation thereof. Movement of the sprung and unsprung masses toward one another is normally referred to in the art as jounce motion while movement of the sprung and unsprung masses away from one another is commonly referred to in the art as rebound motion.
In many applications involving vehicle suspension systems, it may be desirable to utilize spring devices that have as low of a spring rate as is practical, as the use of lower spring rate elements can provide improved ride quality and comfort compared to spring devices having higher spring rates. That is, it is well understood in the art that the use of spring devices having higher spring rates (i.e., stiffer springs) will transmit a greater magnitude of road inputs into the sprung mass of the vehicle and that this typically results in a rougher, less-comfortable ride. Whereas, the use of spring devices having lower spring rates (i.e., softer, more-compliant springs) will transmit a lesser amount of road inputs into the sprung mass and will, thus, provide a more comfortable ride.
In some cases, however, it may be desirable to temporarily increase the spring rate of the spring devices. For example, coil springs that have a progressively increasing spring rate are well known and commonly used to provide added stiffness to a suspension system upon experiencing a sudden impact or other transient input.
In some cases, the spring devices can take the form of gas spring assemblies that utilize pressurized gas as the working medium. Gas spring assemblies of various types, kinds and constructions are well known and commonly used. Typical gas spring assemblies can include a flexible wall that is secured between comparatively rigid end members and/or end member assemblies.
Generally, it is possible to reduce the spring rate of gas spring assemblies, thereby improving ride comfort, by increasing the volume of pressurized gas operatively associated with the gas spring assembly. This is commonly done by placing an additional chamber, cavity or volume filled with pressurized gas into fluid communication with the primary spring chamber of the gas spring assembly. Such additional volumes are commonly retained in constant fluid communication with the primary spring chamber of the gas spring assembly such that a reduced spring rate of the gas spring assembly is maintained.
In other cases, however, it may be desirable to vary the active volume of the gas spring assembly to vary the spring rate thereof and provide different performance characteristics for the gas spring assembly as conditions of use change. In known constructions, such variations in spring rate are commonly initiated or otherwise performed by electronic systems that actuate control valves and other devices in response to sensor signals and other inputs.
Notwithstanding the broad usage and overall success of the wide variety of gas spring assemblies that are known in the art, it is believed that a need exists to confront one or more of these competing goals, to overcome other disadvantages of known constructions and/or otherwise advance the art of gas spring devices while still retaining comparable or improving factors such as performance, ease of manufacture, ease of assembly, ease of installation and/or reduced cost of manufacture.